Bleaching is usually effective in lightning discolourations caused by tobacco, tea, red wine, coffee and age. However, not all tooth stains respond to bleaches. Individuals considering tooth-bleaching treatments should first go through a dental exam to determine the cause of the stains and to ensure that your mouth and gums are healthy. While the procedure is usually performed entirely under controlled dental office conditions, some patients opt for home-use tooth-bleaching systems. The general side effects to tooth bleaching are minimal but they may involve increased tooth sensitivity and gum irritation. Currently available bleaching systems include whitening toothpastes, porcelain veneers, bonding and at-home bleaching kits.